Basically, older Mac OS X CD's have two main partitions. One with the main install (HFS+) and another one with Boot Camp drivers for Windows (FAT32 or just a standard CD format). If you look in the ISO or DMG in the archive.org explorer, it can't read HFS+, only the standard, FAT32 or CD format. That's why it seems like there are only. But to install or reinstall a recent version of OS X, you must either download a non-bootable installer from the Mac App Store or (via OS X’s invisible, bootable recovery partition) download 6GB.
There are several options for installing Git on macOS. Note that any non-source distributions are provided by third parties, and may not be up to date with the latest source release.
Homebrew
Install homebrew if you don't already have it, then:$ brew install git
Xcode
Apple ships a binary package of Git with Xcode.
Binary installer
Tim Harper provides an installer for Git. The latest version is 2.33.0, which was released about 1 month ago, on 2021-08-30.
Mac Os X Lion Installer Download
Building from Source
If you prefer to build from source, you can find tarballs on kernel.org. The latest version is 2.33.0.
Free Mac Os X Installer Download
Installing git-gui
Mac Os X Setup Download
If you would like to install git-gui and gitk, git's commit GUI and interactive history browser, you can do so using homebrew$ brew install git-gui